Mineral-base lubricating oils and methods for using same



Aug. 26, 1958 E. MOODY ETAL MINERAL-BASE LUBRICATING OILS AND METHODSFOR USING SAME Filed Aug. 19, 1953 2 Sheets-Sheet 1 zoCzmSz.. ENRE@ omio owls@ Hm. E.; Q24 m. o ommzoo o o momEwSo MEME 5009 V ISCOSITY (SAYBOLT UNIVERSAL, SECONDS) (SEMILOG SCALE Leonard E. Moody Alexander Hpopkin Inventors L. E. MOODY ET AL MINERAL-BASE LUBRICATING OILS ANDMETHODS FOR USING SAME Filed Aug'. l9, 1953 Aug. 26, 1958 2 Sheets-Sheet2 m0. O. NO. wO. m0.

w... mn Om N wm EQUILIBRIUM OCTANE REQ.

s r w n e V m vm dw OO O DI MH Ea dd rn GG MX e LA By @1LT/7W AttorneyUnited States atent C "ice MINERAL-BASE LUBRICATING OILS AND METHDS EURUSING SAME Leonard E. Moody, Cranford, and Alexander H. Popkin,

Newark, N. l., assignors to Esso Research and Engineering Company, acorporation of Delaware Application August 19, 1953, Serial N0. 375,137

3 Claims. (Cl. 252-32.7)

The present invention relates to improved lubricating oils for use ininternal gasoline combustion engines of the reciprocating type. Moreparticularly, the invention is concerned with improved automotive motoroils which are mineral-base lubricating oil compositions having, incomparison with prior art formulations, reduced tendency to contributeto an increase in the requirement of octane number of gasoline forknock-free operation of high compression ratio internal combustionengines. The invention is also concerned with methods for operatingautomotive engines having compression ratios above about 7.0:1 withthese improved lubricating oils in combination with essentiallyhydrocarbon gasoline fuels, which are essentially hydrocarbon mixtures,under conditions that result in a decrease of the formation ofcombustion chamber deposits of the type which contributes to octanerequirement increase. This invention is particularly concerned withmotor oils containing mineral oil base stocks and addition agentsimproving the characteristics of the composition, in which neither thebase stock nor at least one of the addition agents contributessubstantially to octane requirement increase during the operation ofhigh compression ratio engines.

For several decades considerable attention has been given to theimportance `of maintaining engine cleanliness in the operation ofinternal combustion engines such as those used in automobiles andsimilar vehicles. One aspect of this problem was concerned with theformation of carbon deposits in the combustion chamber of the engine. ltwas found that these carbon deposits reduced the volume of thecombustion chamber thereby increasing the compression ratio and also ledto the formation of localized hot-spots in the chamber that caused theair-fuel charge to ignite prior to the proper time for spark ignition.These effects resulted in knock in the engine.

During the nineteen-thirties it was recognized that, in order toovercome that knock, it was necessary to increase the `octane number ofa gasoline in comparison with that of the fuel required for knock-freeoperation in a clean combustion zone. In studies carried out onautomobiles having relatively low compression ratios, such as thosebelow about 6.5:1, it was also found that the con- '2,849,398 PatentedAug. 26, 1958 ventional oils which were used at that time to lubricatethe engines, contained components that formed carbon in the combustionzone. In characterizing various mineral oil lubricating oil componentsas to their tendency toward carbon deposition affecting octanerequirement increase, the following conclusions were reached: The morehighly aromatic portions of mineral oils generally were conducive tocarbon formation. The high boiling components yof paraiiinic-baselubricants, such as residual stocks called bright stocks, alsocontributed to such carbon formation. For example, in one study aPennsylvania base lubricating oil containing residual components wasfound to increase the octane requirement of new cars in 1935 at a rateof about one octane number per 400 miles operation until the octanerequirement had increased by about 7 to 14 units'.

lt was found that selective extraction of mineral oils with solventssuch as furfural and phenol produced lubricating oils that either didnot contribute or contributed relatively little to this type of octanerequirement increase. Removing certain types of high boiling componentsfrom the bright stocks also improved the finished lubricant.Deasphalting, acid-treating, solvent extraction and other refiningprocesses were used for treating the bright stocks or residuals todecrease their contribution to octane requirement increase. Merrill etal. have given an interesting discussion of this problem (Renner, 14,313 (1935)).

It has been conventional practice for approximately the past twentyyears to employ solvent-refined mineral `oil base stocks in premiumgrade motor lubricants. However, heavy components such as bright stockhave been considered to be necessary ingredients of such oils in orderto improve oiliness characteristics and other properties. Therefore,conventional lubricants have contained minor amounts of bright stocksprepared by deasphalting, dewaXing, acid-treating or solvent extractionof crude oil residues. Such formulations were reasonably satisfactory'as regards knock using the fuels available in relatively low compresisonratio engines, and the engines generally did not require overhauling orcleaning until about 25,000 to 35,000 miles `of operation. Good engineperformance was frequently obtained for even longer periods.

Another aspect of the engine cleanliness problem has been directed topreventing or retarding bearing corrosion, piston ring sticking,cylinder wear, sludge deposition and Varnish formation on various partsof the engine. Noteworthy advances have been made during the pastfifteen years in the development of detergent, viscosity improving,antioxidant, and corrosion inhibiting additives for lubricating oilsthat reduce these and other diiculties thereby increasing engine lifeand improving engine performance.

A new aspect of the general problem of engine cleanliness has appearedduring recent years with the development and widespread use `ofautomobiles and other vehicles having relatively high compression ratioengines, when using modern additive-containing mineral oil lubricants.Users of such vehicles frequently found, after relatively shortoperating periods, that the engines knocked and lost power even thoughpremium additive-containing lubricating oils were used and even thoughfuels having high octane ratings meeting the automobile manufacturersrecommendations were employed. Considerable speculation arose as to whatfactors contributed to these difficulties and to possible solutions forovercoming them. It was generally believed that engine depositscontributed in some manner to these difficulties.

In order to determine the cause of the problem, road tests have now beencarried out under carefully controlled conditions on new cars havinghigh compresison ratio engines (above about 7:1). It was found that thecars which eventually knocked and lost power contained films of darkdeposits having the characteristics of resins in the combustion chamberproper, these deposits forming chiefly on the piston top, on valve tops,and on the underside of the cylinder head. Under these conditions theoctane requirement to prevent knocking increased by as much as 10'-l5units during the first 3,000 to 5,000 miles of service. Power losses ashigh as 10%, as indicated by decreased ability to accelerate, wereobserved. On the other hand, cars containing no such deposits in thecombustion chamber proper did not knock or lose power when using thesame fuel. It was therefore establishedhthat deposits in the combustionchamber proper and not other types of deposits, such as those on thepiston rings and the like, are critical as regards octane requirementincrease.

That combustion chamber deposits of this type are responsible for suchsubstantial effects seems anomalous. They are not strictly speaking ofthe carbon type. Furthermore, careful measurements of the depositvolumes showed thatl the decrease in combustion chamber volume due tothem (and thus the increase in compression ratio) could account for onlyabout l to 15% of the octane requirement increase observed. It was thenfound that temperature effects (heat capacity and heat transfer) accountfor the remainder of the deposit harm. The insulating nature of theseresin-like deposits was found to retain heat in the combustion chamber.Thus, the deposits decrease cooling through the combustion chamberwalls. This results in heating up the ineoming'charge and raises theoverall combustion temperature, whichV in turn makes the engine -moreprone to knock. These effects are due to -thev poor heat conductivity ofthe deposits.

Chemical analyses showed that the combustion cham-ber deposits generallycontained in the organic portion, carbon, hydrogen and oxygen in theatomic ratio of about :5 :2, respectively, with small amounts of sulfurand nitrogen (0.5 to 4% by weight). Lead compounds (as oxides,chlorides, sulfates, etc.) were also present in amounts as high as 50 to80% of the total deposits when the gasoline contained tetraethyl lead(TEL) and halide seavengers for the TEL.

Full-scale road tests with various combinations of lubricants and fuelsestablished that both the fuel andthe lubricant could contribute to thedifficulty. Further tests also revealed that under otherwise constantconditions, mild driving conditions, such as urban and suburban driving,aggravated the 4build-up of deposits. High speed driving and itsattendant higher gas velocity and temperature in the engines appears todislodge the deposits, and the problem is less acute under theselconditions.

This 'problem has serious economic implications. The fuel anti-knockquality has been increased to meet the demands of -new engines, but, inaddition, the octane number must also be increased by the incrementalamount demanded by the same engines after'use. There are several adverseeffects. The car ownermust use al gasoline that is relatively moreresistant torknock and more expensive, than is required for a cleanengine. Otherwise he is confronted with objectionable knocking and powerloss.

Gasoline manufacturers must increase markedly the anti-knock quality offuels now being supplied to satisfy the existing car population. Eachinherently unnecessary increase in anti-knock quality places an undueburden on production facilities, requires relatively more expensiverefining procedures and increases fuel costs to the consumer. Theincremental requirement in octane num ber also limits the extent towhich car manufacturers can increase compression ratios to provide moreefiicient engines which will take advantage of improved anti-knockquality fuels. Thus compression ratios could be increased substantiallyabove present levels if octane requirement increase could be reduced. Itis obvious that a large incentive exists for improving the efiiciency ofoperation of present-day and future vehicles and for minimizing thedeleterious effects Iof octane requirement increase.

It is therefore a principal object of the present invention to teach theuse of motor lubricants that have reduced tendency to cause octanerequirement increase in high compression ratio engines or to cause theformation of poor heat conductivity deposits in the combustion chamber.It is a further object to teach methods of operating such engines withgasolines having specific and critical properties whereby advantage maybe taken of the improved lubricating oils.

A further object of this invention is directed to improved mineraloil-base lubricating oils containing one or more characteristicimproving addition agents in which the base stock and at least one ofthe addition agents do not substantially contribute to octanerequirement increase when used to lubricate high .compression ratioengines.

- These and other objects of the present invention will be amplified inthe following description taken in conjunction with the examples andclaims.

A In accordance with the present invention, it has been found that animportant criterion `of the tendency of the lubricating oil composition,contacting the parts of a combustion chamber subject to friction, toform deposits contributing to octane requirement increase is itsresinification index. The term resinication index as used in thisspecification vand claims refers to the relative freedom of a fuel orlubricant from tendency to form tenaciously adhering resin-like depositswhen subjected to combustionV in a container under a hot, smokeless,flame, e. g., a hydrogen flame, as will be explained in more detailbel'ow.

Full-scale road tests withv new cars have established thatthe extent towhich the lubricating oil forms such resin-like deposits under ahydrogen flame is substantially a' direct function of the extent towhich it contributes to the formation of harmful combustion chamberdeposits. It has 'further been shown that this property is not afunctionof the amount of ash-forming materials present in thelubricating oils andis .not a function of the carbonforming tendency ofthe oil components as measured by conventional tests such as thewell-known Conradson carbon test, the Ramsbottom coke test, etc. Thisproperty to form adherent resins in the combustion zone, while not fullyexplainable at this time, appears to be closely associated with thetendency of a given component to form high molecular weight cross-linkedresins at hot flame conditions of the type prevailing in combustionzones. This cross linking phenomenon appears to derive from the propertyof the component itself as well as from catalytic effects caused byaddition agents in the oil and fuel. These resins not only resistcombustion but-also appear to have a'binding effect in retaining carbonand inorganic substances in the deposits.

With referenceto the present invention, it has particularly been foundthat a superior motor oil composition suitable for use in' present `dayhigh compression ratio engines consists Iof a'v mineral oil basestock'that has a low resinification'indexin combination with'at leastone addition agent that, when ydissolved in the base stock, has also alow resinication index. An oil formulated by this procedure not onlyrcaps the advantages of having improved characteristics imparted by theaddition agent, but also has unexpectedly improved properties withregard to decreased contribution to octane requirement increase inengine use.

A more specific aspect of this invention contemplates a composition inwhich a substantially non-contributing mineral oil base stock hasdissolved therein a-multiadditive system in which at least two of theaddition improving agents do not themselves contribute to octanerequirement increase. Under these conditions it is possible to toleratethe presence of octane requirement increase contributing agents in smallamounts and yet obtain the advantages of this composition.

A preferred composition in accordance with this in- Vention contains asubstantially non-contributing mineral oil base stock and at least threedifferent non-mineral oil addition agents, ,each of which improves adifferent characteristic of the composition without at the same timecontributing substantially to octane requirement increase. Morepreferably, all of the components of the finished composition arenon-contributing to octane requirement increase.

Examples of mineral oil base stocks are relined mineral oil distillatesthat -are free of mineral oil bright stock residuums. It has been foundthat bright stocks, even of the highly refined variety, have highresinication indexes. They contribute substantially to the formation o-fharmful deposits even when present in small concentrations. Although itis known that bright stocks can deposit carbon, as mentioned above, theyhave been used heretofore in concentrations ranging from as low as about5% up to as high as 98% in premium grade mineral oil compositions. It istherefore surprising to find that they are harmful even at lowconcentrations. More particularly, refined mineral oil distillates orso-called neutrals that are substantially free of constituents that boilabove about 600 F. at a pressure of 10 mm. (Hg) absolute, are preferred.The higher boiling mineral oil constituents contribute to the formationof harmful deposits. For example, base stocks boiling within the rangeof about 275 to 600 F. at this pressure are quite useful. Those boilingbelow about 575 F. at this pressure have excellent low resinificationindexes, substantially independent of the origin and chemicalconstitution of the crude oil. The initial boiling point is not criticalas regards deposit-forming characteristics, but it should be high enoughto avoid excessive oil consumption by vaporization when used in themotor.

The discovery that such relatively low boiling base stocks can be usedper se as the only mineral oil component of a finished oil compositionfor high-powered internal combustion engines is unexpected. Prior artformulations using neutral oil components contained bright stockresiduals and other heavy mineral oil components, added to improveoiliness, to increase viscosity and to lower oil consumption, and eventhe neutral oils in these formulations only remotely approached the lowboiling range of the neutral oils of the present invention. The presentbase stocks, however, when formulated with suitable synthetic ornon-petroleum additives, are not only not contributing to the formationof poor heat conductivity deposits, but also give superior all-weathermotor lubricants having excellent viscosity and viscosity indexcharacteristics, low pour-point, good stability, and low oil consumptionwhen used in high compression ratio phospho-sulfurized polyolefns, metaldithiophosphates, phosphosulfurized terpenes, and the like. At least oneof these non-contributing additives will be used in the presentinvention. It is preferred that no more than two, and preferably no morethan one, of a different type of additive that contributes substantiallyto octane requirement increase, be used in combination with thenon-contributing additive. Specifically preferred compositions include acombination of at least two of the above different types of additionagents that are non-contributing with no more than one contributingagent.

It has also been found that substantial improvements in the operation ofautomotive engines and the like having high compression ratios, such asabove about 7:1, and preferably above 7.5 to 1, can be achieved byemploying the lubricating oils of this invention in combination with agasoline fuel having decreased tendency to contribute to octanerequirement increase of the type discussed above, i. e., a fuel having alow resinication index. In general, conventional commercial high octanegasolines containing mixtures of straight run petroleum distillates,cracked naphtha stocks, polymers, tetraethyl lead and the like have highresinification4 indexes and contribute substantially to the formation ofcombustion chamber deposits having low heat conductivity. In some casesthe fuel can almost entirely mask the benefits obtained by using the oilof the present invention.

For example, when using a fuel having a relatively high resinificationindex in combination with an improved oil, octane requirement increasecan be reduced by about two or three units in contrast to performancewith the same fuel and a relatively high resiniiication indexlubricating oil. Although this improvement is substantial, unexpectedlybetter engine performance is obtained by using fuels having lowresinication index characteristics in combination with the improvedoils. For example, a leaded fuel containing low and critical amounts ofsulfur when used in combination with the lubricating oil of thisinvention, will give improved engine operation. Leaded fuels containingcertain high boiling scavenging agents also give superior results.Certain high octane fuels containing no tetraethyl lead are alsosuperior to conventional fuels in this respect. Since aromatichydrocarbon compounds, particularly those boiling above about 300 F.,are harmful for the purpose of this invention, it also contemplatesoperations with gasolines containing relatively low concentrations ofsuch aromatics. The most superior results have been obtained with fuelshaving very lo-w resiniiication indexes.

Various methods for preparing and formulating lubrieating oilcompositions of the present invention and of employing them aslubricants in high compression ratio engines are presented in thefollowing examples. It is to be understood that these examples are givenas illustrations of the present invention and are not to be construed aslimiting the scope thereof in any way.

In the drawings, to be described in detail in connection with theexamples:

Figure 1 is a plot of the viscosity-temperature characteristics oftypical commercial oils and of the SAE 5W-20-type oils of the presentinvention.

Figure 2 is a plot of the effect of sulfur content of leaded gasolineson equilibrium octane requirement.

TESTING PROCEDURES Test 1,-Automotive road test Automobile road testswere carried out to evaluate the performance of various crankcaselubricating oils and gasolines by the following procedure:

The cars used were new 1951 Oldsmobile 88 sedans (compression ratio-7.5:1). The initial octane requirements of the engines were determined,both before and after spark settings were adjusted to the manufacturersrecommendation, usiug the Co-`ordinatingResear-ch" Coun- The cars werevcharged with the gasolines and'lubricatingoils'tobe' tested cilsStandard Uniontown procedure;

and were road tested in caravans, usually consisting'of seven cars, overa'predetermined courseforup to' about' 7000 miles. 50% ofv theaccumulated miles werecity stop-audigo-type driving, and 50% were inintercity,

moderate speed-type` drivingV with top speeds' 'of no' more.

cluding preignition, accelerationtirne, oil'iconsumption,J

fuelco'nsumption, air. fuellratio, et'c. A't the' endof the test, octanerequirement was determined, the engine was dismantled, and thecombustionchambers were photographed and inspected.

Octane requirement was determined-by the Standard Uniontown procedure,CRC'Designation E'-l-943, as described in the C. R. CQ Handbookp, 90 etseq., 19`46 edition. Octanerequirement increase (ORI)` is the differencein the nal and initial octane requirement of the engine.Equilibriumoctane requirement (EOR) is the octanerequirement of theengine after several-thousand miles (usually 5000 miles) of use atWhich'octane requirement reaches a substantially constant level. ORI andEOR are based on road octane numbers usingA primary'reference fuels.

Test 2.-Combuszn test forr'esinifcatowndex This test isv described indetail in copending application Serial No. 352,373, tiled in the name ofAlexander H. Popkin on May 1, 1953, now U. S. 2,761,766. In this test'aknown weight ofI a sample of material to be tested such as alubricatingoil, a gasoline or other material is placedin an open' vesselhaving smooth non-absorptive inner surfaces, such asa glass beaker,porcelain Crucible, etc. gen llame, although other clean flames such asmethane, etc. may be used, is directed into the opening of the vessel.The burner tip, forintroducing the gas and air or oxygen (if needed), isdirected toward the interior of the vessel. The samplef is burned untilonly a dry residue remains. The flame is discontinued and the vessel isallowed to cool. The total weightof the resinous residue is. thendetermined. When testing oils, the interior of thevesselis wipedcarefully, beforeweighing, with avsoft cloth or other soft materialtoremove carbonaceous deposits but to leave the tenaciously adheringresin-like deposits. The total deposits. are weighed when burning fuels.The weight of deposits for a given weight of charge gives theresinilication index. Specic testing conditions used for oils,additive-containing. oils, additives, and gasolines are shown below:

Conditions Oils and Gasoline additives Sample charge, g 5.000 200.0Pyrex beaker size, ec; 250 400 HzzAirratio, in cubic feet/m 0. 1610.120. 59:0 Burning time, minutes -10 25-35 Test 3.-Laus0n engine test Ahot, smokeless, clean llame, preferably a hydro-V CTL secondaryreference fuels using an oscilloscope which gave visual ratings of knockintensity via a sensitive pickup attached tov one of the studs of theengine. This procedure was found to be more accurate than the audiotyperatings usually used'in the Standard Uniontown procedure, becauseknocking in the Lauson engine is difficult to hear. Operations at thelow power level ofv 0.5 b'. kw. gave good' ORI and EOR correlations'with full scale road testsI of the typel described' in Test 1.

The above-described'testing procedures Were used in the evaluationsto'be` discussed in the examples.

DESCRIPTION OF ALUBRICATING OIL BASE STOCKS,. ADDITIVES, AND FUELS Thefollowing discussionv gives information onthesource,composition,inspections, and the like of .the variousmaterials that were: evaluatedv as described in the examples.

A. Oil base' stocks Base'stockf1 -'Ay distillate having a SayboltUniversal viscosity at 210 F; of about4-3 seconds was obtained byconventional distillationof paraflin-base Mid-Continent crudes. Thisdistillate was then extracted with phenol solvent under usualconditions-to obtain about a 60% yieldof ral'linate; The raffinate wasdewaxed using a conventional=` methyl-ethyl ketone-benzene solvent toobtain approximately 67% yield of dewaxed product having a 5 F. pourpoint. .TheI dewaxed product was then distilled tolobtainv a' bottomsfraction designated a-s base stock A.

Base stockBr-Tliisiproduct was obtained by dewaxing theV abovesolvent'ratlinate` to about a 74% yield of dewaxed product havinga'pourpoint of about 15 F. This dewaxed product wasy then distilled toobtain an overhead fraction designated-as base stock B.

Base stockv C.This base stock was a light solvent neutral overheadfraction obtained by the distillation of the same charge'stock used inmaking base stock A.

Base stock D.-Tl1`is base stock was a light solventneutral'overhead'fraction-obtained by distilling the same chargestockiusedin making base stock A to obtain a fraction intermediate basestocksv B and C.

Base. stock E.Thisbase stock was a light solvent neutrali overheadfraction obtained by distilling the same charge stock usedfin makingbase stock A.

Base st0ckF.-This was a Ibright stock residuum obtainedV by conventionaldeasphalting, dewaxing, acidtreating andphenol'fextraction of a residuumobtained fromrth'e distillation of-a Panhandle, Mid-Continent crude.

Base stock G.-Thisba'se stock was a blend containing 92% by volume ofbase stock B and 8% by volume of basestock F.

Basey sto'ck H.'-This base stock was obtained by the sulfuricfacidtreatmentofa lube oildistillate obtained i from a Texas Coastal crude;

Base stock l.-This base stock was also obtained by the sulfuricacid'treatmcnt of a lube oil distillate obtained from a Texas Coastalcrude. v

Base stock K.-A cycle stock was made by catalytic cracking aMid-Continent type 4gas oil using a silicaaluminacatalyst.y This'cycle'oil boiled in approximately the same range as the original gas oilfeed stock. The cycle stock was then selectively extracted with phenolsolvent to a 50% railinate yield. The rainate was solvent dewaxed to a+25 F. pour point, the dewaxed oil yield being based on the solventralinate. The dewaxed oil was then distilled to obtain a 0-27% lightneutral overhead fraction designated as base stock K.

Base slack L'.-This base stock was a ypolybutene having a Staudingeraverage molecular weight of about 400. The polybutene was prepared bythe conventional polymerization of isobutylenei using a Friedel-Craftscatalyst.

Typical.. inspections on the various oil base stocks are shown' in'Table I, below;

TABLE I.-TYPICL INSPECTIONS OFOIL BASE STOCKS Base stock A B O D E E G H.T K L Inspections:

Gravity, API 29.4 31. 9 36. 9 35.0 34. 4 26. 5 31. 1 28. 6 23. 4 34. 036. 5 Flash point, F 475 405 345 360 365 555 410 340 390 355 235Vlscosity, S. U. S. at-

100 F 371 150 66 74 83. 220 192 100 613 81 239 210 F 57. 3 43.8 36.037.0 38.1 145 46. 7 38. 4 57. 2 37. 6 51. 3 Viscosity index. 102 112 107107 107 100 109 48 64 104 120 Pour point, F +15 +15 0 5 +15 +15 +15 35 5+20 50 crue@ source 1) 1) 1) 1) 1) 1) 1) 1) 2) 1) 1) Distillatlon range,F. (10 m g pressure absolute Engler distn.):

Initial boiling point... 420 370 325 320 320 390 376 315 360 (5) Finalboiling ponia (1) eso 50s 555 561 544 645 Temperature at, percentdistilled:

2 483 392 348 343 5 412 366 363 425 380 380 446 398 401 470 411 418 40-490 422 431 50. 511 432 444 60- 533 440 455 70 550 450 466 80 584 460483 90. 614 479 501 95 647 494 526 Sulfur, Weight perce (6) 0.05 (0)Conradson carbon, Weight 0. 1 0. 1 0. 1

1 Mid-Continent. 2 Coastal. 3 Synthetic. 4 Started cracking.

5 Not determined-distilled below 600 F. at 10 mm. Hg pressure.

B. Additives Additive 1.-This additive was a polybutene concentrateviscosity index improver consisting of about 24% by Weight ofpolyisobutylene having a Staudinger average molecular 4weight ot about15,000 and 76% by Weight of a mineral oil base stock consisting of 85%base stock B and 15% base stock C.

Additive 2 This was another polybutylene concentrate consisting of 22%by weight of polyisobutylene having a Staudinger average molecularweight of about 15,000 and 78% by Weight of base stock A.

Additive 3,-This was a commercially available detergent additivecontaining a high proportion of alkaline earth metals (approximately 1.5Wt. percent barium and 2.0 Wt. percent calcium).

Additive 4.--This Was a commercially available polymethacrylateester-type viscosity index improver consisting 1of about 37% by weightof a polymerized C-Cm alcohol ester of methacrylic acid (of about 12,000molecular weight) and 63% by Weight of mineral lubricating oil.

Additive 5.-1`his Was a commercially available antioxidant vconsistingof about 55 weight percent of zinc dialkyl dithiophosphate in minerallubricating oil.

Additive 6.--This was ya commercially available antioxidant consisting`of about 50% of a P2S5-treated alphapinene in a mineral lubricatingoil. The oil concentrate analyzed about 13% sulfur and 4.6% phosphorus.

Additive 7.-'1`his was an ashless detergent additive prepared bytreating a polyisobutene having an Aaverage Staudinger molecular weightof about 1100 With about 10 vweight percent P285 at a temperature ofabout 330- 420 F. for 11 hours. The ltered acidic product, having sulfurand phosphorus contents of about 2.4 and 4.4% by weight, respectively,was used in a mineral oil concentrate containing 60 Weight percentactive ingredient;V

Additive 8.-This additive was prepared by neutralizing the above acidicreaction product, additive 7, with an aqueous solution of guanidinecarbonate at a temperature of about 240-290" F., the resulting productultimately heated to 400 F., total heating time being 6 hours. Theiinished additive was `a 50% concentration yof the active ingredient inmineral lubricating oil. The sulfur content of the active ingredient wasabout 1.7 `Weight percent.

Additive 9A.-This was a commercial detergent addi- .tive containing thepotassium salt of P2S5-treated polybutene and having a potassium contentof 2.6% Iand a phosphorus content of 1.8%

6 Not determined.

Additive 9B.-This was a commercial detergent additive containing thebarium salt of P2S5-treated polybutene, having a .barium content of 4.1%and a phosphorus content of 1.6%.

Additive 10.-This was an experimental polyrnethacrylate-type esteruseful as an ashless detergent additive. It consisted of about 40% byWeight of a polymerized long chain aliphatic ester of methacrylic acidin mineral lubricating oil. The active ingredient appeared to have anempirical formula of about C127H248O13-2N.

Additive 71.-This was a pour depressant containing as the activeingredient a coplymer of the fumarie acid ester of coconut alcohols andof vinyl acetate in an /20 weight ratio. It was a 20% by weightconcentrate in a lubricating oil.

C. Fuels Fuel 1.-This fuel was a synthetically prepared isooctane.

Fuel 2.-This was a parat-linie fuel consisting of a blend of isopentane,alkylate and virgin mineral oil naphtha.

F del 3.-'i'his was a motor gasoline comprising a blend of isopentane,catalytic, and virgin naphthas.

Fuel l.1 -This Was a commercial grade unleaded fuel.

Fuel 5.**This was a blend of a hydroformed naphtha and a lightcatalytically cracked naphtha.

Fuel 6.--This fuel consisted essentially of diisobutylene.

Typical inspections on the above unleaded fuels are shown in Table Il.These fuels, both with and Without about 2 cc. TEL (plus halide-typelead scavenging agent) Were used in the various tests described below.

TABLE II.TYPICAL INSPECTIONS OF GASOLINE FUELS I (NO TEL) Fuel number 12 3 4 5 6 Gravity, API.... 71.3 71.8 63.5 00. 2 53.0 64.3 R. P., p. s. 11.8 9.3 8.2 10.4 3.7 1.3 Research octane No 99.1 79.0 85. 6 90.0 91. 5(1) Motor octane No 98.8 77.3 76.6 79.9 79.8 85.8 Sulfur, weight percentO. 024 0. 056 0. 034 0. 028 0. 024 Olens,

cent 3.8 40. 7 36. 3 39 100 Aromatics, weight ercent 0 4. 2 9. 3 18. 222 0 Engler distillation? B. 205 95 100 93 136 205 50% ofi, F 210 214208 228 363 216 F. B. 264 372 376 414 434 235 1 Equivalent to iso-octaneplus 0.3 ce. TEL. 2 Atmospheric pressure.

11 EXAMPLE I.-COMBUSTION CHARACTERISTICS OF LUBRICANTS AND ADDITIVES Aseries of Lausonengine and-road tests were carried out using various oilbase stocks, oil blends, and additives as the motorlubricants whenrunning the motors with fuel l (isooctane). This minimized anycontribution by the fuel tofoctane requirement increasey since;tests hadshown that iso-octane does not lead to theformation of harmfulcombustion chamber deposits. Equilibrium octane requirements weredetermined from these tests. Hydrogen combustion tests were also carriedout on various materials. Lauson engine EOR data were converted by astandardized correlation to field test BOR levels in order to obtaindirect comparisons. The comparative results are shown in Table III,below:

TABLE III Reslniii- Equilibcation brium index, Oil base stock, oilblend, or additive tested octane mg. resin/ requtre- 5 g. oil

ment (combustion test) Base stock L (polybutene) 79 2 Base stock C (l) 4Base stock C+10% additive 1 78 1 15,000 M. W. polybutene per se 2. (1)0v Additive 2 (l) 0.6 Base stock D-i-11% additive 2- 78 (l) Base stockK+10.5% additive l 78 (l) -98% overhead cut of base stock B 3. 84 7 Basestock B 86 i8 Base stock .T 83 13 Base stock C+% additive Erl-0.2%additive 6+ 10.5% additive 2 .T 83 17 Base stock H+5% additive 3-1-0 2%additive 6+ l 10.5% additive 2 83 17 Base stock G 90 38 l Notdetermined.

2 Active ingredient of additives 1 and 2.

3 Obtained by distllling base stock B.

The deposits formed in the combustion tests, after wiping olii the loosecarbonaceous deposits, were generally light colored resinous materialsinsoluble in organic solvents. The deposits in the combustion chambersof the cars andLauson engines were resinous-base deposits (as shown bytheir insolubility in solvents) containing carbon or other darksubstances imbedded therein. In some cases flaky, dark deposits coveredthe resin-base. However, although the two types of `deposits did not,have exactly the same appearance, an excellent correlation was obtainedbetween the amount of resinous deposits as determined by the hydrogencombustion test and the EOR in actual engine tests.

Lube oil base stocks and additives having low resinilication indexes donot contribute to ORI. Lubricating oil base stocks having resinicaticnindexes below about mg./ 5 g., preferably below 5 mg./5 g., giveoutstanding results. Additives having low resiniiication indexes, suchas below l0 ing/5 g., are greatly preferred. A useful method for testingthe contribution of a particular` additive is to carry out a combustiontest on a blend of the additive at a desired concentration in a nonORI-contributing oil base stock. This will give information on thetendency of the additive to contribute to ORI, regardless of the type ofbase stock eventually empolyed for the additive.

Finished additive-containing lubricating oil compositions preferablyhave a resinication index below about mg./5 g., although those having anindex level below 10, more especially below 5 nig/5 g., will givesuperior engine performance.

EXAMPLE IIi-COMBUSTION CHARACTERISTICS OF FUELS A series of engine testswere also carried out on various types of gasolines using a lubricatingoil: having a resiniiication index of about 4 mg./5 g. ResinicationHYDROGEN COMBUSTION TEST WITH AUTOMOBILE FIELD TESTS Resiniiica-Equilibrition index, um octane. mg. deposit requirein hyd.

ment

Fuel l l Fuels contained no tetraethyl lead.

The correlation between equilibrium octane requirement and resinifcationindex is quite good. Generally at a resinication index below about 40mg./200 g., particularly below 20 mg./200 g., octane requirementincrease could be maintained below about 3 units. When similar testswere carried out on the saine fuels containing tetraethyl lead,resinication indexes were much higher, particularly if the fuelcontained appreciable sulfur.

EXAMPLE III.EFFECT OF BRIGHT STOCK.ON OCTANE REQUIREMENT INCREASE Roadtests were carried out using oil base stock B and base stock G (a blendof base stock B and base stock F) as lubricating oils using iso-octaneas fuel. Equilibrium octane requirements for each oil (average rating oftwo'A cars) are shown below:

Amount Equiliboi bright rium Base stock stock in octane oil, vol.requirepercent ment B 0 84v G 8 90 The highly rened bright stockcontributed aboutone unit increase in octane requirement for each onepercent added to theoil.

EXAMPLE IV.-EFFECT OF BOILING RANGE OF MINERAL OIL BASE STOCK ON OCTANERE- QUIREMENT INCREASE Road tests (test 1) were carried out usingiso-octane as fuel and several of the base stocks of Table I as oils.Base stocks B and J per se were used. Base stocks C, D, K, and H eachwere blended to contain either additive 1 or additive 2 in order toincrease their viscosity and viscosity index. Octane requirementincreases are shown below in Table V:

TABLE V Base oil B C D K J H .Additive in oil, percent:

l olybutene conc.) 0 11 0 10. 5 0 7 2.(polybutene conc.).. 0 0 11 0 0Type of base stock (1) (1) (l) (l) (2) (1) Boiling range of base oil (10mm.

Hg absolute):

I. B. P., F 370 325 320 (t) 360 315 F. B. P., F 660 508. 555 (3) 645 544Octane requirement increase 5. 5 0 0 0 5. 5 0

F. at 10 mm. Hg pressure gave no octane requirement ais-19,398

I3 increase, regardless of whether they were Mid-Continent or Coastaltypes. Those boiling above about 600 F. at 10 mm. (about 500 F. at 1 mm.Hg pressure) contributed substantially to octane requirement increase.

EXAMPLE V.-EFFECT OF VARIOUS ADDITIVES ON OCTANE REQUIREMENT INCREASEField tests and Lauson engine tests were carried out on blends ofVarious additives in non-ORI contributing ybase stock C usingsubstantially non-contributing fuels in the operation of the engines.The EOR of this base stock and of ORI contributing base stock B areshown for comparative purposes.

A comparison of the eect of various viscosity index improvers is shownbelow in Table VI:

TABLE VI Approximate octane Amount of V. I. improver in base stock C,requirement increase Weight percent Lauson Car field tests None (basestock C per se) l 1 1 1 11% additive 2 (polybutene) 0 0 8% additive 4(polymethacrylate est 10 2 9 None (base stock B) 9 2 9 1 Estimated fromresinication index of 4 mg./5 g. 2 Estimated from Lauson-field testcorrelation.

The polybutene-type viscosity index improver, as shown previously,4 wasnon-contributing to ORI in both the Lauson and full-scale tests. Thepolymethacrylate ester additive contributed slightly over one unitoctane requirement increase for each percent present. It is interestingto note that the use of the ORI contributing additive in base stock C isabout equivalent to the performance of ORI-contributing base stock B.The combination of a low ORI contributing oil base stock with at leastone low ORI contributing additive gives greatly superior results.

A comparison ot' the eiect of various detergent-type additives is shownbelow in Table VII. These additives were blended in non-ORI contributingoil base stocks C, D or E, and tested in Lauson engines. Substantiallynon-ORI contributing fuels were used in Vthese tests.

1A11 blends adjusted to SAE 5W-2O grade by addition of 7-11% additive 2.

Both the unneutralized phospho-sulfurized polybutene and thepolymethacrylate ester type detergent additives contributed to octanerequirement increase. The phosphosulfurized polybutenes that were atleast partially neutralized with either ashless or ash-forming basicreagents gave excellent performance. Commercial additive 3 contributedsubstantially to ORI.

Full-scale iield tests were also carried out on oil compositions inwhich either a non ORI-contributing base stock (either base stock C orE) or an ORI-contributing base stock (base stocks C or E containingabout 5% base 14 stock F (bright stock)) were blended with variousadditives. The cars were operated with ORI contributing fuel 3containing about 2 cc. TEL/gallon. The results of these tests are shownin the table below:

1 All compositions contained about 5% additive 3.

The use of a non-contributing base stock gave a noticeable decrease inEOR in comparison with the contributing base stock regardless of theadditive system used, even though an ORI-contributing fuel was used.When the non-contributing additive (additive 2) was used in themulti-additive system in combination with the contributing additive 3,no effective decrease in EOR was obtained in comparison with thecombination of contributing additives 3 and l0 when an ORI contributingbase stock was used. A decrease of about two EOR units was obtained,however, when additive 2 replaced additive 10 in the noncontributingbase stock.

In general, when using a multi-additive system in a substantiallynon-contributing oil base stock, at least one, and preferably more thanone ofthe additives should be substantially non-ORI contributing. Thisapplies particularly to the additives, such as viscosity index improversand detergency improvers, that are present in substantial amounts.

EXAMPLE VLi-EFFECT OF VARIOUS FINISHED LUBRICATING OIL FORMULATIONS ONOC- TANE REQUIREMENT INCREASE A number of mineral base lubricating oilscontaining various types and concentnations of additives were tested infull-scale car tests (test 1) and Lauson engines (test 3). Theformulations follow:

Formula 1 Component: Amount, weight percent Base stock D (74 S. U. S. at100 F.) 85.3 Additive 3 5.0 Additive 6 0.2 Additive 1 7.0 Additive 4 2.5

Formulations with solvent neutrals of this type have the followingtypical inspections:

Flash point, F 385 Pour point, F -35 Stable pour point, F -20 S. U. S.viscosity at 0 F 3200 S. U. S. viscosity at l00 F 165 S. U. S. viscosityat 210 F 50.4 S. U. S. viscosity at 300 F 38.2 Viscosity index Formula3This was also an SAE 5W-20 grade, oil.

Component: Amount, weight percent Base stock C (66 S. U. S. at 100 F.)84.3 Additive 3 5.0 Additive 6 0.2 Additive 2 10.5

Formula 4 This was also an SAE 5W-20 grade oil.

Component: Amount, weight percent Base stock D (74 S. U. S. at 100 F.)84.8 Additive 1 10.0 Additive 8 5.0 Additive 6 0.2

Road tests and Lauson tests were carried out'on some of the aboveformulations using various types of fuels.

The following road tests were carried `out using fuel 3 containing 2 cc.tetraethyl lead/ gallon. A commercially available Pennsylvania-basemotor oil (about 60S- U. S. at 210 F.) was also run. Results are showninfTable VIII, below:

TAB LE VIII Average Number equilibrium Lubricant o cars octane testedrequirement Commercial Pennsylvania-base oil 2 95 Base stoc 4 92 Formula3 6 89 The oil of the present invention (Formula 3) was clearly superiorto the others. The higher boiling mineral oil components in thecommercial oil and base stock- G contributed from 3 to 6 units moreoctane requirement than the light mineral oil. It is to be noted thatall of these tests were carried out with a high ORI-contributing fuel.

The results shown in Table IX, below, were obtained with fuels that didnot contribute substantially to octane requirement increase.

All of the formulations, (l) to (4), free from bright stock, weresuperior to base stock G. The Formula 4 SAE 5W-20 oill containing theguanidine neutralized detergent additive (additive 8) gave especiallygood performance superior to the others containing ORI-contributingdetergent additive 3. It is seen that in a multiadditive system,significant improvements are obtained by using two rather than only onenon-ORI contributing additive in combination with the non-ORIcontributing oil base. This is particularly significant when theadditives, as is the case here, are used in relatively large amounts.

EXAMPLE VIL-EFFECT OF FUEL COMPOSI- TION ON OCTANE REQUIREMENT INCREASERoad tests and Lauson engine tests were carried out by the procedure oftests 1 and 3 on various gasolines having relatively low aromaticcontents, both unleaded and containing TEL uid (2 cc. TEL per gallon).The gasolines contained varying amounts of sulfur. A motor oilnon-contributing to octane requirement increase was used in these tests.In the following Table X, all data are reported on the basis of roadtest results.

TABLE X Equilibrium octane Weight perrequirement Fuel cent sulfur infuel Clear Leaded uel fuel High sulfur fuel 1 0.065 80 88 Fuel 3(commercial) 0.056 80 87 Fuel 6 (diisobutylene) 0. 024 77 84 Fuel 2(paranie) 0. 024 77 83 Fuel 1 (iso-octane) 0. 0008 78 77 1 Similar tofuel 3 but containing more sulfur.

No substantial octane requirement increase was obtained in the cleargasolines regardless of sulfur level. With leaded fuels, as shown in theplot of Figure 2 of sulfur content vs. equilibrium octane requirement,large decreases in octane requirement take place at sulfur levels belowabout 0.025% especially below about 0.01% by weight of sulfur. However,it was found that combustion chamber deposits formed with low sulfurcontent, leaded gasolines. This finding leads to the conclusion that inthe absence of sulfur, TEL uid leaves deposits that have anti-knockproperties which offset the proknock effect due to their thermalinsulating properties and volume. When sulfur is present, lead sulfateand possibly other lead salts having no anti-knock properties areformed. This causes octane requirement increase.

Similar test were carried out on low-sulfur fuels containing aromaticand non-aromatic hydrocarbons of various types, with and without TEL. Ingeneral, paraflins, olefins and naphthenes were found not to contributeto the formation of harmful combustion chamber deposits, even though TELis present. Low-boiling aromatic hydrocarbons, such as benzene andtoluene are relatively harmless components from the standpoint of ORI.The higher aromatics are less desirable, the extent of contribution toincreased octane 'requirement increasing as boiling point and molecularWeight increases. For eX- ample, 40% by weight of mixed Xylenes in anon-contributing fuel will increase octane requirement by 6-8 units. 40%of a hydroformate fraction (55% aromatics, boiling above about 300 F.)in the same fuel contributed an octane requirement increase of about 10units.

Therefore, the amount of aromatics boiling above 300 F. should bemaintained at low levels in the preferred fuel mixtures. Lower boilingaromatics, particularly those boiling between about 250 to 300 F. shouldnot be present in amounts above about 20%, based on the total fuel.

EXAMPLE VEL-EFFECT OF OPERATING AUTO- MOBILES WITH CONTRIBUTING AND NON-CONTRIBUTING FUELS AND LUBRICANTS The following data (Table XI)illustrate the effect of operating with a combination of contributingand noncontributing lubricating oils and fuels.

asa-asas' TABLE XI Approximate octane requirement increase Lubricatingoil Fuel No.

Misc-octane) 6 1 Contained 2 ce. TEL/gallon.

The combination of the typical commercial, high ORI contributing oilbase stock G, containing bright stock, with a non-contributing fuel gavea decrease in octane requirement of 2 units over the combination of bothcontributing oil and fuel. The combination of a low ORI-contributing oilof this invention (Formula 3) with a contributing fuel gave a decreaseof 3 units. it would therefore be expected that the combination of anon- ORI contributing fuel and the W-ORI contributing lubricant wouldgive at most a reduction of only about 5 units. Actually an unexpectedimprovement of 8 units was obtained. Even greater improvements can beobtained by using a non-ORl contributing oil with a non-ORI contributingfuel.

The following Table XlI presents the levels of equilibrium octanerequirement obtainable with various cornbinations of mineral baselubricants and fuels of varying degrees of contribution. EOR data arereported at eld test levels regardless of Whether the tests were run inLauson engines or full scale engines.

1 Contained about 0.056% sulfur and 2 cc. TEL/gal.

fIso-octane contained 2 cc. TEL/gallon and 0.014 wt. percent added Suiibid-octane contained 2 cc. TEL/gallon and about 0.0008% sulfur.tielliriroula 4 containing 5 Wt. percent additive SlB instead of 5%addi- A deiinite improvement was obtained using an oil having a mediumtendency to contribute to Gill when using a high ORI fuel. Betterresults were obtained with either low or medium ORI oils of thisinvention when used in combination with medium ORl fuels. The bestresults, as shown previously, were obtained with low ORT( fuels andlubricants- It is interesting7 to note that a low-sulfur, leaded fuel(iso-octane plus TEL), when used in combination with a low URIcontributing,y oil gave very little ORI increase.

Oils (l) and (4) not only gave superior performance as low-ORIcontributing oils but also had excellent engine cil consumptioncharacteristics for such low viscosity oils. Oil consumptions much lessthan one quart per 500 miles were consistently obtained in the fieldtests.

EXAMPLE IX Lauson engine tests were carried out with a motor oil havinga resinification index of about 4 mg./5 g. in one case the fuelconsisted of fuel 3 (containing 0.056 wt. percent sulfur), 2 cc. TEL/gallon,` and 1.5 stoichiometric equivalents (to make lead=halide) of anethylene chloride ethylene bromide scavenging agent mixture. An EGE. cf

l@ about 69 Was obtained. ln another case, with the same fuel containing2 cc. TEL/ gallon and 1.5 stoichiometric equivalents of mixedmono-bromoxylenes, and EOR of about 60 was obtained. It is seen that theuse of the highboiling scavenging agent, bromoxylene, in the highsulfur,leaded fuel, in combination with a loW OR oil, gave much superior engineperformance in comparison with the same fuel containing low-boilingscavenging agents.

EXAMPLE X A bright-stock free, SAE SVV-20 oil was formulated consistingessentially of 87.5 volume percent oil base stock C, 10.5 vol. percentadditive l, 0.2 vol. percent additive 6, 1.3 vol. percent of a mixedcalcium-barium salt of tert.octyl phenol sulfide and 0.5 vol. percentalka line calcium petroleum sulfonate (about 950 average molecularweight). This oil composition had a resinitication index of below 20nig/5 grams oil and a viscosity index above 150. Two cars were testedwith this oil by the procedure of test l using fuel 3 containing 2 cc.TEL/ gallon. An average oil consumption level of about 700 miles perquart oil and an average EOR of about S7 was obtained in these tests.The combination additive, metal alkyl phenol sulfide-metal petroleumsulfonate, imparted excellent detergency characteristics to the oil.Metal alkyl phenol suliides, especially the alkaline earth metal salts,either alone or in combination with oil soluble, alkaline earth metalpetroleum sulfonates, are-useful detergent additives in the oils of thepresent invention. Additives of this type are taught in such U. S.Patents as 2,362,289; 2,362,291; 2,379,241; 2,409,686; and 2,480,664.

The non-contributing mineral lubricating oil base stocks used in thepractice of the present invention may be obtained from Mid-Continent,Coastal, Middle East, Pennsylvania, and the like crudes, butMid-Continent distillates having good viscosity characteristics arepreferred. These are preferably distillates that have been refined byconventional procedures to remove the bulk of the relatively morearomatic, carbon-forming constituents (such as measured by the Conradsontest), and that have also been treated to remove those constituents thatform resins when subjected to combustion undera smokeless flame asheretofore described, to give a final product having a resiniicationindex below about l0 mg./5 g. The conventional refining proceduresuseful for removing the more aromatic portions, sulfur and other harmfulcon stituents include treatment with mineral acids, such as sulfuricacid; treatment with alkalis; solvent refining with various solventssuch as phenol, furfural, sulfur dioxide, and the like; treatment withaluminum halides; extraction With silica gel; clay treatment;hydrogenation; desulfurization such as hydrotining; propaneprecipitation; solvent dewaxing; catalytic cracking; etc.

The resin forming constituents remaining in these rened distillates areprobably higher molecular weight paraffinic-naphthenic orparafhioaromatic compounds although their exact yconstitution is notunderstood at this time. Therefore it is generally desirable to use acombi nation of refining methods to `effect substantially completeremoval of them. Thus a lubricating oil distillate obtained from asuitable crude may be distilled to obtain a fraction of approximatelythe desired boiling range, acid-treated or solvent extracted (anddewaxed if neces'- sary to remove high pour point constituents) and thenredistilled to remove resinifying heavy ends.

Another suitable source of mineral oil base stocks is in refinedcatalytically cracked cycle stocks. Such cycle stocks are the morerefractory hydrocarbons that resist cracking to lower boilingconstituents when residual hydrocarbons, gas oils or other relativelyhigh boiling hydrocarbons are cracked in the presence of metal oxide catalysts or the like. The cycle oil that has been recycled through thecracking zone several tnnes is withdrawn, refined for the removal of therelatively more aromatic constituents, dewaxed if desired, and distilledto recover a fraction of the proper boiling range and viscosity. Suchrefined fractions are stable, low sulfur content materials that makeexcellent base stocks per se or may be blended with other mineral oildistillates to form suitable base stocks. White oils, i. e., mineraloils refined with fuming sulfuric acid for the complete removal ofaromatic-type constituents, may also be used as blending agents for thebase stocks.

The preferred mineral oil base stocks of the present invention are thosefrom which mineral oil components boiling much above about 600 F. (in asimple distillation at a pressure of l mm. Hg, which corresponds toabout 890 F. at a pressure of 760 mm. Hg) have been removed. A suitableboiling range is within the range of about 275 to 575 F., or preferablywithin about 300 to 575 F., at 10 mm. Hg pressure absolute, with lessthan about to 10% of components boiling about 550 F. The lower end ofthe boiling range will depend to a large extent on oil consumptioncharacteristics of the lubricant, and generally components boiling muchbelow about 275 to 300 F. at 10 mm. Hg absolute are too high involatility for use in most high compression ratio internal combustionengines. The distillation test is ASTM Method D1160-52-T.

The above lower boiling oils are particularly useful in formulating SAE5W-20 oils. In the event higher viscosity oils, such as SAE W-30 gradeoils, are desired to reduce oil consumption in the engine, blends of thelow-boiling stocks and higher 'boiling stocks may be made that meet bothresiniiication index and viscosity requirements. Thus a blend of 60%light solvent neutral having a resinification index of about 3 and of40% of a solvent refined distillate having an S. U. S. viscosity at 100F. of about 150 and a resinification index of about 20 will have aresinilication index below about 10 mg./5 g. and meet certain highviscosity requirements. It will be realized that this inventioncontemplates base stock blends made from various components providingthe base stock is low in ORI contribution. It is also preferred that thebase stocks have viscosity indexes above 100 in order to make premiumgrade lubricants. For this reason oils that have only been refined Ibyacid treatment are less preferred than the extracted Mid-ContinentMiddle East and other such high V. I. oils. Base stocks having pourpoints below about F. are also preferred.

An example of a suitable SAE 10W-30 oil is one in which the base stockis a 50-50 mixture of oil base stocks B and D (described above)containing of 5 different additives for V. I., detergency, corrosioninhibition, antioxidant and pour point improvement, and in which one ofthe additives, constituting a major portion of the additive system, hasa resiniication index below 5 mg./5 grams. The total lubricating oilwill have a resinifcation index below 2O mg./5 grams, S. U. S.viscositiles at 0 F., 100 F., 210 F., and 300 F., rsepectively, of10,000; 356; 69.3; and 44.5 and a V. I. of 140.

In order to meet viscosity specifications required of suitable oil basestocks, it is preferred that these stocks have a viscosity in the rangeof 50 to 160 S. U. S. at 100 F. and of about 33 to 50 S. U. S. at 210 F.If the base stock is to have a viscosity of much above 40 S. U. S. at210 F., relatively narrow cut distillates, such as those boiling in therange of about 400 to 550 F., 450 to 600 F., 500 to 575 F., and the like(at 10 mm. Hg absolute) may also be used to reduce the concentration ofhigher boiling, ORI-contributing components. Mineral oil base stockshaving less than about 5 to 10% of components boiling below 390 F. at 10mm. Hg are preferred from the standpoint of oil consumption.

Other suitable base stock constituents and blending agents which may beused in combination with mineral oils of the type described include lowresinification index hydrogenated oils, synthetic oils resemblingpetroleum oils (polymerized olefins, synthesis products from the Cirreaction of oxides `of carbon with hydrogen or from hydrogenated coals,shale oil derivatives, etc.), synthetic polyester and polyether-typelubricants and the like. Synthetic oils include esters made from amonohydric alcohol and a monobasic organic acid or diesters made fromalcohols dibasic acids. Specific examples include di-Z- ethyl hexylsebacate and di-Ca Oxo alcohol sebacate. Alcohols include the C7, C9,C10, C11, C12 and C13 alcohols made by the Oxo process from olelins.Suitable dibasic acids include adipic, azeleic and sebacic acid. Complexesters made fro-m a monohydric alcohol, a dihydric alcohol (glycol) anda dibasic acid may also be used. Polyalkylene oxide-type synthetic oilswith suitable terminal alcohol groups, complex formals, mercaptals andtheir esters, and the like are also useful.

Oil base stocks containing synthetic lubricating oils preferably consistof a major portion of a suitable mineral oil base stock of the typedescribed with only minor amounts of low resinication-indexsynthetic-types of blending agents having lubricating oilcharacteristics. Generally less than 10 to20% 'by weight of synthetic ornon-petroleum oil blending agents of the type described, based on thetotal base stock, will be used.

The additive components useful in the practice of the present inventionto formulate finished lubricants must be selected with great care notonly from the standpoint of the specific characteristic of the oil to beimproved but also with regard to the extent to which the additive itselfwill contribute to octane requirement increase at the concentrationlevel needed to improve a specific characteristic. It is preferred thatthe multi-additive system have a resinification index below 20 mg./5grams, preferably below 10 mg./5 grams. Useful systems include those inwhich at least two different additives constituting a major portion ofthe additive system have a combined resinification index below 5 mg./5grams. Especially useful mixtures of additives, preferably three or moredifferent types, will have resinilication indexes below about 5 rng./5grams. The following paragraphs will give due consideration to suitableadditives with particular emphasis being placed on the types that havelow resinilication indexes when blended with various oils.

One of the most important additive materials used with the base stock ofthe present invention is a viscosity index improver. The finishedlubricating oil should have a high viscosity index. To achieve this itis usually essential to add a non-mineral oil constituent that willimprove these characteristics Without at the same time contributingsubstantially to the ORI of the engine using the oil. A preferredviscosity index improver as well as thickening agent is a high molecularweight hydrocarbon such as an olefin, including the polymerized C3 to C5olefins. For example polymerized butenes and preferably polymerizedisobutylene having a molecular weight in the range of about 5,000 to50,000, preferably about 10,000 to 25,000, are quite useful. Thesepolymerized olens are readily prepared by procedures well known to theart. These addi-tives are especially suitable for increasing theviscosity of light neutral Ioils and other light distillates. Forexample, oils having S. U. S. viscosities below about 40 at 210 F. maybe increased to higher viscosity oils such as those having viscositiesabove about 45 S. U. S. at 210 F., by the use of these V. l. thickeningagents. In order to increase viscosity and to improve viscosity index ofthe finished lubricant by as much as 10 to 70 units, it is generallydesired to employ in the range of about 0.5 to 30.0 weight percent,preferably 1 to 15%, of the polyolen based on the finished lubricatingoil. Other viscosity index improvers include the polymethacrylateesters, fumarate-vinyl acetate copolymers, polyalkylstyrenes, and thelike. Since the polymerized esters generally contribute to octanerequirement increase, they are less preferred than the polymerizedolefins as viscosity index improvers. As a general rule,ORI-contributing types may be used in amounts below about 3%,

preferably below 1.0% by weight. Finished .lubricants containing amixture of polyolelins and polyesters may be formulated to avoidsubstantial increases in octane requirement. Thus from 3 to 10% ofpolybutene and 0.5 to 3% of a polyester may be used. However, it is muchpreferred to employ only the oleiins as viscosity index improvers.

Another important additive to be employed in the tinished lubricatingoil of the present invention consists of at least one detergencyimproving additive. These agents will help maintain oil insolubleoxidation products and the like suspended in the oil and will in generalimprove engine cleanliness.

A wide variety of detergency improvers may be employed. One class ofadditives for this use consists of the phosphorus and sulfur-containinghydrocarbons prepared `by treatment of an essentially hydrocarbonmaterial with a sulfide of phosphorus or a combination of the elementsphosphorus and sulfur. These reaction products are Well known to theart.

As a general rule, the desired hydrocarbon, such as a paran, an olen, anaphthene, an aromatic, a terpene, hydrocarbon resins, high molecularweight polymerized oleiins, mineral oils such as lubricating oildistillates, and the like are treated with a sulfide of phosphorus usinga ratio of about one mole of phosphorus sulfide for 1 to 10, preferably2 to 5, mols of hydrocarbon at a temperature in the range of about 275to 550 F. The resulting reaction product may be used as such, but it ispreferred to refine it further by treatment with a suitable agent suchas by reaction with a basic reacting material or by reaction With anesterication agent. Suitable basic reacting materials include thealkaline metal and alkaline earth metal oxides, carbonates, hydroxides,hydrides and the like, specifically, po-tassium, sodium, barium, andcalcium compounds. Basic inorganic compounds of heavier metals may beused, such as those of molybdenum, tin, zinc, chromium, manganese,nickel and the like.

Suitable ashless treating agents include nitrogen bases such as ammonia,and organic nitrogen bases such as amines and amine derivatives,guanidines and their derivatives, morpholine, pyridine, quinoline andlike substances. Guanidine and its derivatives are particularly useful,the symmetrical tri-substituted compounds such as trialkyl, triphenyland trinaphthenyl guanidines and the like being useful. Other usefulcompounds include the biguanides, dicyandiamides, dicyandiamidines,hydrazines, ureas, thioureas, semicarbazides, thiosemicarbazides maleateand fumarate esters, aminoalcohols, acrylonitrile, alcohols, vinylesters, phenols, oletins such as diisobutylene, dipentene and the like.Such treating agents are disclosed in the art such as U. S. Patents U.S. 2,613,205; 2,640,030; and 2,640,053.

Treatment of the product with these and other agents may be carried outat any suitable temperature, such as from about room temperature up to400 F. o-r so using suiiicient treating agent at least to partiallyneutralize, esterify, or combine with the titratable acidity of thephosphosulfurized material. Completely neutralized materials are usuallypreferred.

The essentially hydrocarbon material to be treated with the combinationof phosphorus and sulfur is preferably one that itself has a lowresinirication index. Thus paraliins, `oleins, naphthenes, neutral oilsand the like give better results than aromatics, bright stocks, etc. Thehydrocarbon to be treated preferably has a resinitication index belowabout mg./ 5 grams.

In a preferred embodiment, the phosphorus and sulfur containing productis obtained by treating a high molecular Weight olefin such as apolyisobutene having a molecular weight in the range of about 300 to30,000 with the sulfur and phosphorus containing agent, followed bytreatment of the acidic product with one of the agents outlined above.Those obtained by treatment with alkali and alkaline earth hydroxides orguanidine or one "2@ of its substituted derivatives and the basicreacting salts thereof, such as guanidine carbonate, are specificallyuseful. These reaction products not only give superior detergencycharacteristics but do not contribute to the formation of harmfulcombustion chamber deposits.

The treating procedure may be varied in several different Ways. Forexample, the acidic phosphosulfurized hydrocarbon may be hydrolyzed bytreatment with steam followed by treatment with the treating agent. Thepartially or completely neutralized products may be hydrolyzed by steamtreatment, or the neutralization and hydrolysis may be carried outsimultaneously. Hydrolysis in general reduces sulfur content,particularly helping to remove unstable sulfur, and improves theresinification index characteristics of the additive.

Other detergents that may be used in the practice of the presentinvention include metal soaps, metal organic sulfonates such ashydrocarbon sulfonates including metal salts of petroleum sulfonicacids, metal phenates, metal alkylates, metal alkyl phenol sullides suchas barium tert.-octyl phenol sultide, phosphates, dithiophosphates andthiophosphites, metal xanthates and thioxanthates, mixtures of these andother agents, coneutralized mixed metal additives such as coneutralizedpetroleum sulfonates and phenolic compounds, such as alkyl phenolsulfdes, etc.

Since detergent additives are usually employed in rather large amounts,from as low as about 0.5 up to 10.0 or 15.0% by weight, based on thetotal oil, specific attention must be given to the extent to which theparticular detergent additive will contribute to resin-type combustionchamber deposits. Many commercial detergent additives are harmful inthis respect, and oils containing only noncontributing types are greatlypreferred. Mixtures of both contributing and non-contributing types arealso useful, in which case a blend consisting of a major portion of anon-contributing additive with only minor amounts of a contributingadditive may 'be used. A mixture of non-contributing types is acombination of the alkali or alkaline earth metal salt of a phosphorussulfide-treated polybutene, such as a barium or potassium salt, and aguanidine neutralized phosphorus sulfide-treated polybutene.

In order to minimize oxidation characteristics of the oils of thepresent invention, it is generally desired to add a small amount of asuitable anti-oxidant or bearing corrosion inhibitor additive. Some ofthe detergent additives listed above have anti-oxidant characteristics,but in other cases they may adversely affect this property of thelubricant. Here again the type of additive employed is preferably onethat does not substantially contribute to octane requirement increase.

Particularly useful additives in this respect are lower olelinichydrocarbons, particularly terpene hydrocarbons, that have been treatedwith a sulfide of phosphorus or with a combination of sulfur andphosphorus by the procedure described above. A specifically preferredadditive is prepared by treating alpha pinene w-ith phosphoruspentasuliide. This product may be used in amounts in the range of about0.05 to 2.0% by weight in the finished composition without harmfuleffects. `Other anti-oxidants include metal and non-metal salts ofdihydrocarbon dithiophosphates, such las zinc dialkyl dithiophosphate,and lamine dialkyl dithiophosphates, phenols, such as alkyl phenols,bis-alkyl phenols and the like, phenol sultides -such a tert-alkylphenol suliides, metal dithiocarbamates, phenothiaz-ine and itsalkylated derivatives, sulfohalogenated olefins that have beendehalogenated by known means, such as diisobutylene treated with asulfur chloride followed by dehalogenation, sulfur-ized dipentenes, etc.Various combinations of these and other well-known antioxidants andcorrosion inhibitors may be used.

The yamount of anti-oxidant employed in the finished lubricant willdepend to a large extent on the type of base stock and the types ofother improving agents added 23 thereto. As a general rule, in the rangeof about 0.01 to 5.0% by weight, based on the total composition, willsuflice to minimize the deleterious effects of oxidation. In the eventthe particular anti-oxidant contributes substantially tooctanerequirement increase, it is preferred that it be used in smallamounts in combination with a noncontributing anti-oxidant.

A pour depressant additive is preferably employed in small 'amounts inorder to meet pour point specifications. This additive should be onethat not only reduces the pour point substantially when used in smallconcentrations but `should also be relatively stable in this regard whenthe oil is subjected to alternate cycles of heating and cooling; i. e.,have a good pour point stability. Such pour point depressants includethe chlorinated wax naphtha-iene condensation products, various polymersand copolymers of unsaturated esters and the like. These additives aregenerally used in rather small amounts, in the range of about 0.01 to2.0 weight percent based on the total composition. Such small amountswill not generally contribute to the octane requirement increasedilliculty discussed above,

`Other agents than those that have been mentioned may also be present inthe composition, such as dyes, oilness agents, anti-rust agents,plasticizers and defoamers, extreme pressure agents `and the like.Suitable anti-rust agents, for example, include the partial esters ofpolyhydroxy compounds such as the oleate of sorbitan, polyglycerols,etc.; Lorol mercapto-acetic acid; ditriricinoleates; alkyl phosphoricacids; acid phosphates, etc. Although the above additives have beendescribed in connection with specific characteristic improvingproperties, it will be recognized that some of them havemulti-functional properties and will improve two or more characteristicsat the same or different concentration levels. The above constitutesonly a partial list of the many additive improving agents `useful in thepractice of the present invention.

The finished oils of the present invention will be compounded to includeat least one substantially non-ORI contributing additive, yalthough two,and preferably three or more different types of additives are generallydesirable to formulate compositions meeting all ot the requirements ofmodern high compression ratio engines. Based on the total composition,the additives will usually constitute a minor amount, yand generallywill be present in amounts below about 25% by weight, preferably about 3to 20% by weight. The base stock of the present invention will make upthe remaining portion of the lubricating oil. The finished oil willpreferably have a resiniication index below about 20 mg./5 grams,especially below l5 :ng/5 grams.

The gafsolines to be used in the high compression ratio automotiveengines 'and the like lubricated by the oils of the present inventionmay be any suitable high octane, essentially hydrocarbon gasoline suchas one having an ASTM Research octane number in the range of about 75 to100. -In a preferred aspect of the present invention, however, thegasoline will have `a reduced resinicaton index in comparison withconventional commercial fuels. It is particularly preferred that thegasoline be one that will contribute no more than about octanerequirement units, preferably below one unit, increase when used incombination with the preferred lubricating oils of the presentinvention.

Conventional components may be used in formulating such gasolines. Thesecomponents include straight run distillates from various types ofcrudes, alkylates prepared by the alkylation of olens with isoparans;high octane polymers prepared by the catalytic polymerization of lowermolecular weight olens; hydroformates prepared by hydroformingnaphthenic-type hydrocarbon distillates to form high octane aromaticcomponents; reformed gasoline fractions prepared from straight rungasolines using conventional platinum catalysts, metal oxide catalystsand the like; catalytic cracked naphthas prepared by cracking 24 gasoils, residuals, etc., in the presence of metal oxide catalysts such assilica-alumina, silica-magnesia, and the like; and various other typesof components that are conventionally employed in gasolines. Suchgasolines are usually formulated by mixing two or more of the abovegeneral types of components in order to form gasolines meeting octaneerequirement, vapor pressure, stability, and other specifications.

It has generally been found of the various hydrocarbon compounds presentin gasolines that paraflins, naphthenes and olefins will not contributesubstantially to ORI. Aromatic components, particularly those having aboiling point higher than toluene contribute substantially to octanerequirement increase. Those boiling above about 300 F. are especiallyundesirable for this purpose. Therefore it is preferred that thegasoline contain no more than 20% by weight, of aromatic hydrocarbonsboiling above about 300 F., and more especially less than 20% by weightof aromatics boiling above about 250 F.

Lead tetraethyl is used in most commercial gasolines in concentrationsranging from about 0.1 to 3.0 cc./ gallon in order to increase octanenumber. Lead scavenging agents such yas ethylene dibromide 'and ethylenedichloride may be present in such compositions.

It has been found in the past that the presence of substantial amonts ofsulfur in the gasoline is deleterious to the effectiveness of tetraethyllead for increasing the octane number of gasoline. It has therefore beenpreferred that leaded fuels contain below about 0.20% by weight,preferably about 0.1% by weight, of sulfur. lt has now been found thatunexpected advantage in decreased ORI can be `achieved by lowering thesulfur content of gasoline critically below the level at which thesulfur has any effect on the actual octane number of the v gasolinecontaining TEL. For minimizing `ORI it is important `to decrease thesulfur content of leaded gasoline below about 0.02%, `and preferablybelow about 0.005% by weight. This may be achieved by treating thevarious components that go into the gasoline, in order to reduce thesulfur content to relatively non-contributing amounts.

Treating procedures for sulfur reduction include prompt caustic washingof the sulfur-containing material in the absence of oxygen soon after acatalytic cracking operation; hydroning of cracked naphthas in which thenaphtha is treated with a catalyst in the presence of hydrogen; treatingnaphtha with formaldehyde at elevated ternperatures, with or withoutsulfuric acid; and treatment of sulfur-containing naphthas with finelydivided sodium in the presence of secondary or tertiary alcohols, ethersor kctones; and the like. The extent to which any or all of thecomponents treated will of necessity depend on the amount of sulfurcontained in each of them and the amount of the particular componentgoing into the gasoline blend. It is preferred to employ a fuel thatcontains relatively small amounts of sulfur as heretofore described, andnon-contributing amounts of aromatics when the fuel is leaded withtetraethyl lead.

Excellent results can be obtained with the lubricating oil of thepresent invention when it is operated in an engine in combination with aclear gasoline, i. e., one that contains no tetraethyl lead. In thisevent the amount of sulfur present in the fuel is not extremelycritical.

In order to minimize the contribution of a conventional leaded gasolinecontaining a normal complement of sulfur, say above 0.1% by weight, alead scavenging agent that is relatively high boiling may be added tothe fuel.

Although it is conventional to use such materials as etlitoluenes;3,4-dichlorocurnene; 1,2-dibromobenzene; 1,2,4-

trichlorobenzene; 2,4-dichlorotoluene, their mixtures and the like.Higher boiling means those agents having substantially the volatilitycharacteristics of tetraethyl lead; preferably they have vapor pressuresat 120 F. of about 0.5 to 5.0 mm. Hg. In excess of about 0.5, preferablyabove about 1.0 stoichiometrical equivalents of these agents, based onthe TEL, may be added to the fuel. Such higher boiling scavenging agentsare taught in U. S. patents including 2,496,983; 2,574,321; 2,479,900;etc.

The gasoline fuel may also contain other addition agents such asantioxidants, gum inhibitors, solvent oils, rust inhibitors, metaldeactivators, etc.

This invention has particular application to the operation of automotiveengines and the like that have compression ratios above about 7:1, andis particularly applicable to those having higher compression ratios,for example 7.5 to l and as high as 12 to l and higher. Such engines areextremely susceptible to octane requirement increase as mentionedheretofore, especially when they are run under rather mild conditionssuch as stop and go city traic, suburban driving at relatively lowspeeds, and the like. Under these conditions the combustion chamber isparticularly susceptible to deposit formation from resinous formingconstituents in the lubricant and/or fuel. However the invention is notrestricted to automotive engines but will apply generally to theoperation of any relatively high compression engine of this type, suchas those in small motor boats, aircraft and the like whereautomotive-type engines are subject to a substantial amount of mildoperation.

What is claimed is:

1. A lubricating oil composition having a resiniication index less than20 mg./5 gr., comprising at least 75 weight percent of a petroleum oilhaving an initial boiling point above 300 F. and a iinal boiling pointbelow 600 F., both at 10 mm. Hg abs., a viscosity in the range of 50 to160 S. U. S. at 100 F. and in the range of 33 to 50 S. U. S. at 210 F.,a pour point below 15 F. and a resiniiication index less than 10 mg./5gr., and up to 25 Weight percent of additives improving the propertiesof said composition, said additives including in the range of 1 to 15weight percent of a. viscosity index improver selected from the -groupconsisting of polyoleins having a molecular weight in the range of 5,000to 50,000 and polymethacrylate esters; in the range of 1 to 15 Weightpercent of a detergent consisting of a phosphosulfurized hydrocarbonhaving a molecular weight in the range of 300 to 30,000 neutralized witha metal containing reagent; and in the range of 0.01 to 5 Weight percentof a zinc dialkyl dithiophosphate as an antioxidant.

2. The lubricating oil composition of claim 1 wherein said viscosityindex improver is a polyisobutylene having a molecular Weight in therange of 10,000 to 25,000.

3. The lubricating oil composition of claim `1 wherein said detergentinhibitor is a barium salt of a phosphosulfurized polyisobutylene.

References Cited in the le of this patent Relationship BetweenVolatility and Consumption of Lubricating Oils in Internal CombustionEngines, U. S. Dept. of Commerce, Technical Paper 500, 1931; page 16pertinent.

1. A LUBRICATING OIL COMPOSITION HAVING A RESINIFICATION INDES LESS THAN20 MG./5 GR., COMPRISING AT LEAST 75 WEIGHT PERCENT OF A PETROLEUM OILHAVING AN INITIAL BOILING POINT ABOVE 300*F. AND A FINAL BOILING POINTBELOW 600*F., BOTH AT 10 MM. HG ABS., A VISCOSITYIN THE RANGE OF 50 TO160 S. U. S. AT 100* F. AND IN THE RANGE OF 33 TO 50 S. U. S. AT 210*F.,A POUR POINT BELOW 15*F. AND A RESINIFICATION INDEX LESS THAN 10 MG./5GR., AND UP TO 25 WEIGHT PERCENT OF ADDITIVES IMPROVING THE PROPERTIESOF SAID COMPOSITION, SAID ADDITIVES INCLUDING THE RANGE OF 1 TO 15WEIGHT PERCENT OF A VISCOSITY INDEX INPROVER SELECTED FROM THE GROUPCONSISTING OF POLUOFINS HAVING A MOLECULAR WEIGHT IN THE RANGE OF 5,000TO 50.000 AND POLYMETHACTYLATE ESTER; IN THE RANGE OF 1 TO 15 WEIGHTPERCENT OF A DETERGENT CONSISTING OF A PHOSPHOSULFURIZED HYDROCARBONHAVING A MOLECULAR WEIGHT IN THE RANGE OF 300 TO 30,000 NEUTRILIZED WITHA METAL CONTAINING REAGENT; AND IN THE RANGE OF 0.01 TO 5 WEIGHT PERCENTOF A ZINC DIALKYL DITHIOPHOSPHATE AS AN ANTIOXIDANT.